Bucket elevator apparatus utilized for lifting granular bulk materials such as food grains for storage or for other processing may be generally classified as being either head-driven or boot-driven in their principal mode of operation. Each elevator category typically includes a vertically-oriented endless belt which co-operates both with an upper pulley and with a lower pulley, and to which are attached multiple, spaced-apart, material-carrying bucket elements. The elevator primary drive is operatively connected to the upper pulley in the case of head-driven bucket elevators and to the lower pulley in the case of boot-driven bucket elevators. A suitable housing with supply and discharge openings encloses the bucket elevator pulleys, endless belt, and attached material-carrying buckets.
Heretofore, the type of bucket elevator preferred in the United States has been the head-driven type with the apparatus primary drive being operatively connected to the elevator upper pulley. However, in instances when large vertical-movement distances are involved and the apparatus primary drive is located at a substantial height above ground, accessibility to the drive mechanism for maintenance servicing or replacement is significantly reduced and is to be avoided.
With respect to boot-driven bucket elevator apparatus, substantial belt slippage, belt tensioning control, and belt-to-pulley alignment problems have heretofore been encountered, especially when high rates of material movement (e.g., 32,000 bushels of grain per hour) or large vertical material-movement distances (e.g., 300 vertical feet) are involved. One known, albeit unnecessarily complex, apparatus resolution to such bucket elevator needs is the boot pulley hydraulic drive with included creep-drive and belt take-up features that is disclosed and claimed in U.S. Pat. No. 4,799,584 issued in the name of Hartsuiker, et al.
Accordingly, a principal objective of the present invention is to provide a bucket elevator having a boot pulley with a boot pulley primary drive with a take-up that obtains simplified belt tensioning control and consequential reductions in belt slippage and belt slippage heat generation, belt wear, belt-to-pulley misalignment, cost of elevator manufacture, and cost of elevator drive maintenance servicing and replacement.
Other objects and advantages of the present invention will become apparent from a consideration of the descriptions, drawings, and claims which follow.